Mass spectrometry plays a major role in over twenty research groups at Purdue University. Although most of the activity is in the Departments of Medicinal Chemistry and Pharmacognosy, Chemistry, and Biochemistry, several other research groups are beginning to use mass spectrometry. The Kratos MS-50 mass spectrometer located in the Department of Medicinal Chemistry and Pharmacognosy is a focal point of much of this activity because it is the only high resolution/fast atom bombardment mass spectrometer which is generally available for routine measurements. Funds are requested to purchase equipment which will be added to the existing instrument rendering it capable of state-of-the-art services. Specific additions include: (1) Data acquisition and display system, (2) High-mass magnet, (3) Adjustable beta slit, (4) Collision cell, and (5) Modified source housing. Acquisition of a new magnet is especially important because the existing magnet is faulty and must be replaced. If this instrument becomes inoperable, there well be no means for obtaining high resolution of fast atom bombardment mass spectra at Purdue University. Because of the importance of the Kratos MS-50 to basic research at Purdue, a highly effective system for operating and maintaining this instrument has evolved.